Colored bands on a resistor denote the amount of resistance.
Every electrical circuit from a basic calculator to a new computer requires a few basic electrical components. Electrical components such as resistors and LEDs serve the same purpose no matter what type of circuit they occur in. Each component has different properties depending on whether they occur in series or in parallel in a circuit
Significance
Electrical components each have a role to play in an electrical circuit. You can find the same components in computers or in other consumer electronics. Each electrical component has a symbol used when drawing a circuit diagram. For example, the symbol for a diode or LED consists of a triangle pointing to the right directly followed by a vertical line. Electrical components manipulate the flow of electricity in a circuit; some components resist electricity while others store it.
Types
Resistors cause the flow of electricity through the circuit to slow. They prevent other components, such as LEDs, from an overload of electrical current. Capacitors store electrical current when the current flows in one direction, then release the stored charge when the current flows the other way. LEDs, or light emitting diodes, use a blocked current to generate light using only a little power. An inductor uses a coil to store magnetic energy and opposes changes in current in the circuit.
Units
Even in the United States, units used to describe electrical components generally use metric units and divisions. Prefixes such as "tera," "kilo" and "micro" represent the value of a unit as one trillion, one thousand and one divided by one million respectively. Units for specific electrical properties include "ohms" for resistance, "farads" for capacitance, "amps" for current, "volts" for voltage and "henrys" for inductance. Electrical components usually have a marking specifying how many units the component can handle.
Identification
Each resistor has a marking with a series of four colored bands that denote the total resistance of the component in ohms. The first and second stripe give the first and second digit while the third stripe represents the number of zeros. Each digit corresponds to a different color. The fourth stripe tells the precision of the resistor. Other components such as capacitors and diodes have a white marking with the units relevant to the piece either on the piece itself or on the circuit board.
Materials
Resistors come in several materials: carbon composition, metal film, carbon film and wirewound. Carbon composition resistors create more noise, while carbon film resistors use less power. Wirewound resistors can provide inductance. Capacitors come in a wide range of materials, each coated with a thin layer of metal. Possibilities include polyester, silvered mica, ceramic, mylar, polypropylene and electrolytic capacitors. Inductors use steel or powdered iron cores covered in thin sheets of steel to store current without losses.
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